Ionic conductivity and thermal property of solid hybrid polymer electrolyte composed of oligo(ethylene oxide) unit and butyrolactone unit

Various hybrid polymers composed of oligo(ethylene oxide) unit and butyrolactone unit, such as polymer blend, block copolymer and random copolymer, were synthesized by radical polymerization of poly(ethylene oxide) methyl ether methacrylate (PEOMA) and/or α-methylene-γ-butyrolactone (MBL), and the ionic conductivities and thermal properties of the solid polymer electrolytes using those hybrid polymers and LiN(SO2CF3)2 were investigated. The solid polymer electrolyte using homopolymer of PEOMA (poly(PEOMA)) showed higher ionic conductivity and larger temperature dependence of ionic conductivity than those of the solid polymer electrolyte using homopolymer of MBL (poly(MBL)). The ionic conductivities of the solid hybrid polymer electrolytes were improved at especially low temperature region compared with each homopolymer electrolyte. This result indicates that the decline in the ionic conductivity at low temperature, which is characteristic of PEOMA unit, has been effectively reduced by combining with MBL unit. The poly(PEOMA) and the block or random copolymer electrolytes showed the higher thermal stability than the poly(MBL) and the polymer blend electrolytes.